The guayusa plant is a tree which grows 6–30 meters tall. The leaves are evergreen and 2.5–7 cm long. The flowers are small and white. The fruit is spherical and red, 6–7 mm in diameter. The leaves contain caffeine and other alkaloids.[1]

The plant is grown primarily in Ecuador in the eastern provinces of Napo and Pastaza, but is found in parts of Peru and Colombia. After harvest, the guayusa leaves are dried which allows flavor to develop.[2][4]

Traditionally, some Ecuadorian Kichwa people boil guayusa leaves in water and consume the resulting beverage for its stimulative effects.[2] In addition to drinking cups of guayusa like many Americans drink coffee, indigenous hunters drink guayusa to sharpen their instincts and call it the “Night Watchman" because it helps them stay alert and awake all night.[5] Fresh leaves are used as well as dried leaves, which are dried in rolls and strung together as a wreath resembling a Hawaiian lei.

Chemical analyses in 2009 and 2010 have shown caffeine content in guayusa of 2.90-3.28% by dry weight.[9][10] Guayusa contains all of the essential amino acids for humans and has a “high antioxidant activity,” with ORAC antioxidant values of 58μM per gram, compared to 28-29μM per gram for commercial green teas.[11][12][13]

There have been few published studies on the possible medical benefits of guayusa, but one study has shown that ingesting guayusa helped reduce hyperglycemia and other side-effects of Type 1 diabetes in an animal model.[14]

Michael Harner, the founder of the Foundation for Shamanic Studies describes how “the Jivaro say guayusa is so habituating that before it is offered to a visitor, he is warned that once he drinks it, he will ever always after return to the Ecuadorian Jungle.”[15]

The Kichwa people claim that guayusa induces dreams that foretell whether hunting expeditions will be successful.[16]